Electrically driven propeller pitch change system



Sept. 30, 1952 A. G. FoRsYTl-l' v 2,612,228 2 ELECTRICALLY DRIVEN PROPELLER FITCH CHANGE SYSTEM Filed July 2, 1946 5 Sheets-Sheet 2 Sept# 30, 1952 A. G. FoRsYTH 2,612,228

ELECTRICALLY DRIVEN PROPELLER PITCH CHANGE SYSTEM Filed July 2, 1946 5 Sheets-Sheet 5 nvt/mf? Rc/maman GRn/lm Mayr/4,

Patented Sept. 30, 1.95.2

ELECTRICALLY DRIVEN PaoELLEa PITCH CHANGE SYSTEM Archibald Graham Forsyth, Cheam,'England, as

signor to The Fairey Aviation Company Liml ited, Hayes, Middlesex, England Application July 2, 1946, Serial No. 680,896

In Great Britain July 3, 1945 This invention relates to electrical equipment on aircraft and has for its object a self-contained electrical unit for association with a variable pitch propeller to provide means for varying the pitch of the propeller blades, and to generate current for electrical de-icing devices for the blades and spinner of such a propeller and for heating, lighting and other purposes on the aircraft.

AEquipment for these purposes is described and claimed in the specification accompanying copending application for Letters Patent, Serial No. 63GA07, filed November 23, 1945, now Patent 2,491,172, but the arrangement therein disclosed is such that an armature is rotated at propeller speed and is satisfactory in cases where the propeller rotates at high speed. There is a general tendency, however, towards the reduction of propeller speeds and the increase of current lconsumption necessitating considerable increase in the weight of the generator. By means of the present invention the introduction of a high speed drive permits reduction of the weight and over-all dimensions of the apparatus.

According to the present invention a dynamoelectric machine has its field coils and brush gear mounted on the front end of an aircraft engine, While its armature is arranged to be rotatable freely about the axis of the propeller shaft and to be driven from, and at a higher speed than, the propeller shaft through intermediate gearing.

In such an arrangement the armature may be formed integral with a gear wheel meshing with pinion wheels on spindles carrying second pinions meshing with a gear wheel keyed to the propeller shaft. This arrangement is used to change the gear ratios. In a modification of this arrangement the gear wheelA with which the second pinions mesh may be arranged to be connected with, or disconnected from. the propeller shaft by a magnetic clutch and it may carry further pinions meshing with two gear Wheels one of which is rotatable as one with the propeller shaft and the other of which is rotatable freely about the propeller shaft, has more teeth than its companion, and is lintegral with a gear wheel coaxial with the propeller shaft and meshing with pinions forming parts of pitch changing mechanism for the blades of the propeller.

In the accompanying drawings:

Figure 1 is a fragmentary section on an axial plane illustrating one form of the invention and Figure 2 is an end elevation of part thereof as seen from the position of line II-II, Figure 1,

Figure 3 is asimilar vew to Figure 1 but illus- 4 claims. (o1. 1704160.23)

trating a modied arrangement, the upper part of Figure Li'is an end elevation of part thereof as seen from the position indicated by the line IVe-Iva, Figure 3, and the lower part of Figure 4 is a sectionon the line IV-IV, Figure 3.

Fig. 5 is a circuit diagram of the series field of the dynamoelectricmachine, and Fig. 6 is a circuit diagram of the Vshunt field.

In the form of the invention shown in Figures 1 and 2, there is secured ooaxially on the nose la of an aircraft engine (not otherwise shown) a cylindrical casing b of small axial length, open at its front end and arranged to t freely into a coaxialA flange c projecting rearwardly from a plate d `arranged to the rear of, and rotatable with, a propeller hub e. At the inner periphery of the casing b are mounted the field coils j of a dynamoelectric machine, the armature y of which is mounted on the peripheral flange of a sub-- stantially I-I section rotor. The sides of said rotor section are coaxial cylindrical sleeves h and y', and the web k of said section (which may be perforated or gapped for the sake of lightness) is normal to the axis of rotation. The inner sleeve j of the rotor is rotatably mounted on a fixed coaxial sleeve m surrounding the propeller shaft n and secured to lthe nose `a of the engine. The inner sleeve 7' extends both rearwardly and forwardly from the Web k, and has mounted on its rearward extension a commutator o which c0- operates with brushes p carried by the rear Wall of the cylindrical casing b. The forward extension of sleeve y' is formed at q as a gear-wheel.

Mounted at the rear of the hub e and plate d is a cylindrical gear casing 1' which is fixed to plate d so as to rotate. as one with the hub e. Gear casing r projects rearwardly into the annulus presented by the forward side of the H.

section rotor h, ik. Gear casing 1' hasan enlarged rear opening permitting the forward extension ofthe inner sleeve 7' of the rotor and also the forward end of the fixed sleeve m to project into this gear casing r.

Within the gear casing r and splined near the forward end of the fixed sleeve m is a fixed spider s carrying three equi-angularly spaced sets of bearings t in which are mounted shafts such as u. Each shaft u has at its rear end a relatively large pinionwheel o meshing with the gear wheel q on the forward extension of the inner sleeve of the rotor for changing the 'gear ratio, while each shaft u carries on its front end a relatively7 small pinion w meshing with a gear Wheel :l: keyed on the propeller'hub e; j

Y InV operation, it will be apparent that with 3 sleeve m, spider s, casing b, and field coils f all stationary, rotation of propeller shaft n rotates hub e, plate d and gear wheel Pinions w are driven by rotation of gear Wheel :c and rotary motion is transmitted through shafts u to pinion wheels v which mesh 4with gearwheel "qvformed on the forward portion of sleeve ".i. This rotates sleeve 7' which is part of the rotor carrying armature y. The gear train obviously causes a st ep up in the rotary speed of the rotor and armature y over the speed of rotation uof Athe propeller shaft n.

In the modified arrangement illustrated 'by Figures 3 and 4, the structuregisthesame except for the driving of pinions w. The pinions w (instead of meshing, as shown in.lEig1 1res,1l an d2,

with the gear wheel :r keyed on the propeller hub e), mesh with a gear wheel y forming the outer component of a magnetic clutch-or brake (of the radially acting type as shown generally in Patent-No. 432,209) whichhasanv inner componentasplined.to-asleeve. l I :which mounted on propeller shaft n. and; positioned inside sleeve. :m so as to be-rotatable-as'onefwiththepropeller shaft n. Inner component eiscomprisedof a central portion va' and AOuter portions orshQes a2 radially movable .with respect to the. centralqpor.- tion. Springs (not shown) normally'urge .the outerportions z2 radially outwardlyintoeontact with the inner surface of gear Wheely, buttenerrgization of the. magnetic elements.` of -theclutch .causes radially inward movement vof .shoes.e2and uncoupling .of gear wheel. .z/andportiQnS-.z2- The gear. wheel. y. is formed` on .a rearwardE projection .of a spider I2 rotatably mountedaboutn portion l .of sleeve. H. vSpider. l2 carries threeequieangnlarly spaced Y spindles l 3, on. each of .which-is a widepinion' I4 .meshing Withtwo gearyvheels. l5, I6 disposed side. by Side.

Current 'for 4 energizing magnetic iclullflllea is carried by -iixed wiresn through, abrushrand ring arrangement. 3] to .wires ,32 .carried .by

sleeve Il.

'Gear wheel l5 is.keyed..to.4 the Vrotating .sleeve l I. Yand gear .wheel 1.6 is, rotatablyj mountedon sleeve Il. .'Ihegearwheel lhas more teeth than the gear wheel l5 .(for example three more) .but-the teeth. of bothgearwheelsl' larecut on the same pit'chcirele. .Gear wheellahas .a forward extension l1 formed with .externalteeth aelaaas 4 toothed forward extension l1, I8 from the gear' wheel I6 revolve en bloc with the propeller shaft n and hub e, causing rotation of pinions w as described above.

When the armature y is to be rotated in either directionfor pitch changing pur-poses, the magnetic clutch "y, 7a is enelszedand disengaged by operation of an appropriate control by the pilot,

thus freeing gear y from sleeve H and the pro- VI eller shaft. Through pilot operated automatic `:.con-trciis (see co-pending application referred to I8 meshingwithgear wheels .not. shown) on worm shafts .extendingtangentially with respect to the rootsof. the propeller. blades... the.r roots-,of saidV blades having worm wheels: formed. .therearound. This arrangementpfgearwheels and worm gearing is not illustratedas itis well known and ldoes not form part of thepresentinvenligrl.

In the modification ofFigs:l 3 andllill magnetic clutch y, a isnormally. deenergized tand springs (not shown) .urge outer portionspr., shoes "z2 radially outwardlyv to couple .outer.. shoes. .22

with the inner periphery of .sun Wheeley. thus transmitting rotation fromsleeve' l l; to wheei. y, to gear w, to shaft u, to wheel 1J., Jl.11.0ug,h,.,gear o to 121k. and armature. y. .When this. is. done, the pinions -w areV rotated..,and. ,armature g` is thereby rotated ata higher. sneedthan 'the-propeller shaft in .the manner explained-above'with respect' to Figures. ly .and .2. .A.oontrol -circuit shown in, cofpending application 630,443? :permits the pilot to operate appropriate, switches in la control circuit for. ,the clutch.

When the armature g is .in use .for genera-ting, which is the normal. condition, .thewidepinions 1.4. the two gear. wheels l5, I6 andthe. externally above), the dynamoelectric machine f, y is energizedas a motor. Energization of field coils f :.in'onesense orvtheother by direct current drives armature ,fg .whichdrives the rotor and rotates sleeve j andits .gear wheel q. Gear wheel q ldrives the kpinion wheels v at the rear ends of the shafts u, thereby rotating shafts u and the pin- .ions 'w .at the forward ends of those shafts u to drive the gear wheel/.on the outer component y of themagnetic clutch; and the spider ,l 2fintegral therewith. lhe'wide pnions J4 .are .earned by .spider I 2 and 'they .roll yround on the relatively i aed gear wheel lfof thepair of gear wheels l5, t6. theseoondgear wheel .Iof this p airghas .thereon three more teeth ytlgian `the -xed .gear lwheel l5, it-fcllows .that the second geanwheel L6 `is A rotated relatively tothe first, i. e. the relative positions of the two gear wheels I 5, A.It changeby the angular extent Jof three teeth per revolution of thetspider |12. 'I hisbringsyabout rotation of the gearzwheelt onthe .extension Hof vthe second gear wheel lI -i '.androtation of vthe gear wheels (not shown) entire-pitch changlng ,worm shafts. As. described inthe co-rpending ycase .referred to above, .such rotation-may -be controlled by pitch limitswtches, so vastogive automatic control ofpitch changes.

.The field windings-f. of the dynamoelectric machine f, dmay be ,subdivided-.so thatthewhole may beused for generating purposes or-when maximum power is required for motoring .purposes but,.when.the machine is .usedjor pitch changing with,y constant .speedgoverning onlyy `a part of the field. f need beemployed thusreducing. current consumption. lThe .circuits for accomplishingthis .are 4shown in .Fidgs 5 ande, Whereinare seenthe twenty-fourv poles .of the machine, ,twelve .of which are seriesand the -,other twelve .of which are shunt. Thefeven numbers f2, fait, etc. .up to fZfi comprise. the .seriesfield, While, the .odd numbers fl, f3, vJ5,. etc. up to f23 comprise the .shunt field. All -coils ,are connected vfor maximum output ,atllyolts- ,For 24 volt supply,.the use. of .coils f5, fl l, Ill. and f2.3 in theshunt circuitandallseries coils is required, this being control led.byav control relaylnot shown) in t'he .master controlunit (not` shown). When the relay is off .effective coils f SVfli, jiji, and fareoperatve for-.24 volts. When the relay isvOlL-a'll coils become effective for volts.

Whenv .the machine fg1is lto .beusedas amotor, .current vmay be supplied theretofrmiaccumulators but, in `the .case of. a .multi-propeller. aircraft, switch ,mechanism may .be provided to enable the outputl vfrom theY dynamoelectric machines assoelated with theengines of some of .the propellers to be fed to the. dynamoeleetric .machines associated with the..engines..of .other .propellers so that they may be used as .motors for pitch changing. purposes.

4vItisto be'notedthat in allformsof the present invention the means bywhichthe armature g of the. .dynangoelectric .machine ad is driven.. .from

the propeller shaft n are such that the armature g is driven at a higher speed, so that without increasing the weight of the dynamoelectric machine or the space which it occupies, it may be used on aircraft, the propeller shafts of which are rotated at slower speeds than those contemplated When use is made of the mechanism forming the subject of the above-mentioned co-pending application for Letters Patent, Serial No. 630,407.

I claim:

l. In an aircraft having a fixed nose part and a propeller shaft projection therefrom, a dynamoelectric machine having its field coils non-rotatably mounted on said fixed nose part about the axis of the propeller shaft, a sleeve attached to and projecting forwardly from said nose part coaxially with the propeller shaft, an armature for said machine rotatably mounted on said sleeve for free rotation with respect to said shaft, a step-up gearing to drive said armature at a higher speed than said propeller shaft comprising a first small gear integral with said armature, a second larger gear keyed to the propeller shaft, a small pinion supported by said sleeve and driven by said second gear, and a larger pinion driven by said small pinion, said larger pinion meshing with-said first gear to rotate said armature.

2. In an aircraft having a fixed nose part and a propeller shaft projecting therefrom, a dynamoelectric machine having its field coils non-rotatably mounted on said fixed nose part about the axis of the propeller shaft, a sleeve attached to and projecting forwardly from said nose part coaxially with the propeller shaft, an armature for said machine rotatably mounted on said sleeve for free vrotation with respect to said shaft, a step-up gearing to drive said armature at a higher speed than said propeller shaft comprising a rst small gear integral with said armature, a second larger gear keyed to the propeller shaft, a small pinion supported by said sleeve and driven by said second gear, and a larger pinion driven by said small pinion, said larger pinion meshing with said first gear and a magnetic clutch interposed between said propeller shaft and the gear teeth of said second gear for selectively connecting and disconnecting said second gear with said propeller shaft.

3. In an aircraft having a xed nose part and a propeller shaft projecting therefrom, a dynamoelectric machine having its eld coils non-rotatably mounted on said fixed nose part about the axis of the propeller shaft, a sleeve attached to and projecting forwardly from said nose part coaxially with the propeller shaft, an armature for said machine rotatably mounted on said sleeve for free rotation with respect to said shaft, a step-up gearing to drive said armature at a higher speed than said propeller shaft comprising a first small gear integral with said armature, a second larger gear keyed to the propeller shaft, a small pinion supported by said sleeve and driven by said small pinion, said larger pinion meshing with said first gear, a third pinion, means mounting said third pinion on said second gear, third and fourth gears arranged side by side in mesh with said third pinion, said third gear rotatable as one with said propeller shaft and said fourth gear being mounted for free rotation about the propeller shaft and having more teeth than said third gear, a pitch changing gear Wheel integral with said fourth gear, and a magnetic clutch interposed between said propeller shaft and the gear teeth of said second gear for connecting and disconnectingsaid second gear and the propeller shaft, whereby connection of the second gear with said propeller shaft causes rotation of said armature from the propeller shaft through step-up gearing, and disconnecting of the second gear from the propeller shaft permits use of said dynamoelectric machine as a'motor to drive said pitch changing gear wheel from said dynamoelectric machine.

4. In an aircraft having a propeller equipped with pitch changing mechanism and mounted on a propeller shaft, the combination of a rotary dynamoelectric machine operable selectively as a' motor and as a generator and having a stator and a'rotor mounted about the propeller shaft. a first gear iixedly mounted on and rotatable as one with said shaft, step-up gearing means connecting said first gear to said rotor and drivable from said shaft for driving said rotor at a higher rotary speed than the propeller shaft, and second gearing means connecting said rotor through said first gear to said pitch changing mechanism and operable for driving said pitch changing mechanism from said rotor when said machine is operated as a motor, and a clutch interposed between said shaf-t and the gear teeth on said first gear for selectively coupling and uncoupling said stepup gearing and the propeller shaft, thereby providing selective operation of said machine.

ARCHIBALD GRAHAM FORSYTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

